The invention relates to an improved brake proportioning apparatus for limiting, restricting and proportioning the application of brake pressure to the wheels of a vehicle under certain conditions.
Devices commonly used to program fluid pressure in brake systems comprise fixed ratio pressure reducing valves. These devices function as a result of an area relationship and as such are capable of only responding linearly to a linear input. Further, as the reduction ratio approaches either unity or zero, the devices become significantly difficult to design and to maintain within pescribed operating conditions.
An object of the present invention is to overcome the disadvantages of known brake proportioning devices. Another object is to provide a brake proportioning device which can provide non-linear programming of fluid pressure to the wheel cylinders. Still another object is to provide a brake proportioning apparatus which is not limited to functioning as a result of a fixed area or ratio relationship and which utilizes spring rates and spring forces in its operation.
A further object of the present invention is to provide a device which can provide either linear or non-linear proportioning of brake fluid. A still further object is to provide a device in which the programming of fluid pressure can be adjusted and the device thus can be utilized with a wide range of vehicle sizes, weights and loading characteristics.
The above and other objects are achieved in accordance with a preferred embodiment of the invention in which a pair of springs are utilized as the differential force mechanism to proportion the flow of fluid pressure through a valve. The springs, which can be either linear or variable in pitch, operatively cooperate with a piston and valve to provide the desired linear and/or non-linear programming of fluid pressue in the device.
Other objects, features, advantages and embodiments of the invention will become apparent from a review of the following specification, drawings and claims.